The objectives and methods are: 1). to determine structural and functional roles of lipids in Leishmania species, by determining the qualitative and quantitative distribution of lipids in the various organelles (kinetoplast-mitochondrion, pellicle, endoplasmic reticulum, nucleus flagellum), of promastigotes in culture in chemically-defined media under various environmental conditions, and of amastigotes in the host. Chromatographic and spectrometric analyses will be used. 2.) to correlate lipid composition and metabolism of leishmanias with their ability to cause cutaneous, mucocutaneous, or systemic infections.